It is possible to create an LTE network where certain base stations are backhauled using a wireless, LTE-based connection. For example, U.S. Pat. App. No. 20140233412, which is hereby incorporated by reference herein in its entirety, describes a network suitable for use by public safety personnel that uses mobile base stations equipped with LTE backhaul modules that establish encrypted LTE backhaul connections to provide voice, data, and multimedia services. Tunneled backhaul is particularly useful for mobile base stations, as mobile base stations are by definition mobile and do not have access in all cases to wired backhaul. Instead they may depend on the ability to utilize wireless backhaul connections over, e.g., Wi-Fi, 3G, LTE, or other wireless protocols.
LTE has two QOS mechanisms, including the Quality of Service Class Indicator (QCI) and Allocation Retention Priority (ARP), that operate on the level of a specific individual packet connection between a user equipment (UE) and a core network, e.g., an Evolved Packet System (EPS) bearer.
The QoS Class Identifier (QCI) controls packet forwarding treatment (e.g. scheduling weights, admission thresholds, queue management thresholds, link layer protocol configuration, etc.), and is typically pre-configured by the network operator. QCI is a scalar associated with an EPS bearer and used as a reference by various bearer-level packet forwarding treatments and filters. These filters indicate the type of flow, e.g., voice, general IP packet data, or media-based IP packet data. A mobile network operator uses the QCI of each bearer to determine what type of treatment is required for the bearer; this is often performed in an IP-based network by translating QCI to another IP-based QOS tagging scheme, such as IP Differentiated Services (DiffServ) code points (DSCPs), detailed in IETF RFC 2474, which can be provided different levels of service within the network.
ARP is also associated with an EPS bearer, as is QCI. ARP contains information about the priority level, preemption capability, and preemption vulnerability. The primary purpose of ARP is to decide whether a bearer establishment or modification request can be accepted or needs to be rejected due to resource limitations. The ARP value can be used to cause a certain bearer to be terminated (preempted) to permit a higher-priority bearer with a higher-priority ARP value to be established. ARP can be part of the subscriber profile which is retrieved from the HSS. Further information about QCI and ARP appears in 3GPP TS 23.401.
Often, operators use the PGW to map traffic onto EPC bearers with associated QCIs, which are mapped to DiffServ classes, and marks IP headers of the packets to reflect these priorities. During congestion, core and backhaul routers drop packets according to non-3GPP rules, such as according to DSCP diffserv code points.